CARD Briefing Paper 99-BP 26
Availability and Market Penetration
of GMO Corn Soybeans
Bruce A. Babcock
Mike Duffy
Robert Wisner
September 1999
Center for Agricultural and Rural Development
Iowa State University
Ames, Iowa USA
Availability and Market Penetration of GMO Corn and Soybeans
This new generation of corn and
soybean seed that enables farmers to better
control pest damage could be the leading
edge of a technological revolution that
changes the way farmers produce crops and
changes the characteristics of those crops.
The uncertainty about whether these crops
are the leading edge or simply a trial run that
goes nowhere arises not because of scientific
uncertainty−scientists are certain that many
new seeds will become available−but rather
because of uncertainty about the extent of
consumer acceptance of food produced
using genetically engineered seed.
For corn, there are four main products
that express Bt, a protein that is toxic to
lepitopteran insects (moths and butterflies
whose larvae are caterpillars).
1. KnockOut and NatureGard. Bt toxin
gene: CrylAb. Genetic event name:
176. Developed and marketed by CIBA
Seeds (now Novartis), and Mycogen.
Approved for sale in August 1995.
Commercial sales started in 1996.
2. Bt-Xtra. Bt-toxin gene: CrylAb.
Genetic event names: DeKalBt and
DBT418. Developed and marketed by
DeKalb (now part of Monsanto). It was
approved for sale in March 1997 and
commercial sales started in 1997.
3. YieldGard. Bt toxin gene: CrylAc.
Genetic event names: Mon810 and
Bt11. YieldGard was developed by
Monsanto and Northrup King (now
Novartis) and is marketed by Pioneer
Hi-Bred, Cargill, DeKalb, and Golden
Harvest. The Monsanto event was
approved for sale in December 1996,
the Novartis event in October 1996,
and commercial sales started in 1997.
4. StarLink. Bt toxin gene: Cry9C.
Genetic event name: CBH-351.
StarLink was developed by AgrEvo.
The event was approved for sale in
May 1998. Sales started in 1998.
There are two corn products that are
resistant to herbicides. The benefit of a
herbicide-resistant crop is that a broad
spectrum herbicide can be sprayed as a postemergent herbicide without stunting the
crop.
1. Liberty Link corn resistant to
glufosinate-ammonium. Developed and
marketed by AgrEvo. Approved in
January 1997. First year of
commercialization 1997.
2. RoundReady corn resistant to
glyphosate. Developed and marketed
by Monsanto. First year marketed was
1998.
There is one soybean product that is
resistant to herbicides.
1. Roundup Ready soybeans resistant to
glyphosate. Developed by Monsanto.
First year of commercial production
was 1996.
USDA’s Economic Research Service
conducts surveys of seed use by region. This
table shows USDA estimates of adoption
rates from 1996 to 1998.
2 / Babcock, Duffy, and Wisner
Adoption Rates for GMO Seeds in the United States and Central Cornbelt
United
United
United
Corn Belt
States
Corn Belt
States
Corn Belt
States
1996
1996
1997
1997
1998
1998
Corn
% acres planted with
Bt seed
1.5
1.4
8.1
7.6
19.4
19.1
% acres planted with
herbicide resistant seed*
0.01
0.03
Soybeans
% acres planted with
herbicide resistant seed**
6.9
7.4
14.7
17.0
44.3
44.2
*Excludes acreage planted to herbicide resistant corn obtained by traditional breeding but
developed using biotechnology techniques that helped to identify the genes.
**Estimates reported for Roundup Ready soybeans in 1996 are much higher than estimates from
Monsanto.
No reliable estimates are available for
1999, although press reports citing industry
sources commonly use 55 percent of
soybeans planted to Roundup Ready seed
and 35% of all corn planted to Bt corn,
Roundup Ready corn, or Bt-Roundup Ready
corn.
Data from a 1998 USDA cost-ofproduction survey were used to examine the
economic impact of GMO crops at the farm
level. This survey was a cross-section of
randomly selected corn and soybean fields
in Iowa. In 1998 more than 40 percent of
Iowa soybean acres were planted with GMO
soybeans. Of the farmers surveyed, 52
percent said they planted GMO beans to
increase yields through improved pest
control. Twenty-seven percent said they
used GMO soybeans to decrease pesticide
costs, and another 12 percent cited increased
planting flexibility. The average yield
reported for the GMO soybeans was 49.3
bushels per acre. The non-GMO soybeans
averaged 51.2 bushel per acre.
There are more genetic modification
options available in corn. In 1998, 24
percent of the Iowa corn acres were planted
to Bt corn, 14 percent had some other
genetically modified seed, and the remaining
62 percent used conventional seed. More
than three-fourths of the farmers using Bt
corn said they did so to increase yields.
Another 7 percent said they used it to reduce
pesticide costs, and the remaining 16 percent
gave some other reason. Increased yields
with Bt corn did occur in 1998 in Iowa. Bt
corn averaged 160.4 bushels per acre
whereas the non-Bt corn averaged only
147.7 bushels per acre.
Even though reports indicate that about
35 percent of the 1999 U.S. corn crop was
planted to GMO varieties, the usable percent
of the crop that is non-GMO is uncertain.
Some observers say that many fields were
planted with alternating strips of Bt and nonBt corn to provide a refuge for corn borers
so that Bt resistance would not develop. The
alternating strips would have cross-
Availability and Market Penetration of GMO Corn and Soybeans / 3
pollinated and would be co-mingled during
harvest. Others in the industry indicate that a
significant part of the refuge corn was
planted in adjoining fields (maximum of
one-fourth mile away, and equal to a
minimum of 20 percent of the Bt acreage),
which would result in less co-mingling.
Either way, the effective supply of GMO
corn (including old-crop co-mingled grain)
may be considerably above 35 percent of the
total.
For soybeans, the situation is slightly
less complex. Cross-pollination is not a
concern for soybeans, and refuge strips are
not a problem. Reports indicate that 55
percent of this year’s soybean acreage was
planted to GMO varieties. Allowing for comingling of the old-crop carryover (which is
about 12 percent of the total supply),
perhaps 30 to 35 percent of the total U.S.
soybean supply is non-GMO.